Pen clip



FIG. 1 is a front bottom side perspective view of a pen clip showing my new design, with the phantom lines depicting environmental structure and forming no part of the claimed design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side elevational view thereof which is a mirror image of the left side thereof; and,

FIG. 4 is a top plan view thereof. 

The ornamental design for a pen clip, as shown and described. 